Monday, 31 October 2011 - Monthly Climate Summary for Perth - Product code IDCKGC11L0

Perth in October 2011: A warmer and wetter month

• Rainfall: Average to above average.
• Maximum temperature: Above average for most sites and 3rd warmest on record for Perth Metro.
• Minimum temperature: Above average.

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Rainfall

Rainfall across the Perth metropolitan area during October 2011 was near average or slightly below average in the southern suburbs, but the rest of the Perth area saw above to very much average rainfall. Rainfall totals were generally in the 30 to 80 mm range, and Rottnest Island received 75.6 mm, which was more than double its long-term average for October, and Rottnest Island's wettest October in 16 years. Perth Metro, Perth Airport, and Pearce RAAF also registered their highest October rainfall total in 12 years.

A middle level disturbance brought light showers to most sites in the Perth area during the first three days of October, though a couple of sites in the southern suburbs received rainfall of more than 10 mm. Isolated falls from showers and thunderstorms occurred in Perth between the 7th and 10th, with a notable fall of 24.6 mm at Jandakot on the 9th, whilst cold fronts on the 13th and 18th brough rain to the metropolitan area although falls were generally light. A series of middle level disturbances in the latter part of the month brought some significant falls to the Perth area. Shower and thunderstorms occurred on the 22nd, and on the 24th to 27th, with daily totals in the 10 to 30 mm range on the 25th and 27th. Daily rainfall of 30.0 mm at Pearce RAAF on the 25th was the highest daily total of the month for the Perth area.

Perth Metro recorded 64.2 mm on 9 rain days in October 2011, compared to the long-term average of 52.2 mm on 8.8 rain days. October rainfall totals have ranged from 1.0 mm in 1969 to 199.9 mm in 1890 at Perth Metro, whilst last October (2010), Perth Metro recorded 20.6 mm on 5 rain days.

For the year to date, Perth Metro has recorded 756.0 mm of rainfall on 95 rain days in the first 10 months of 2011, which is below the average of 815.1 mm, but despite this is the wettest January to October period in 6 years, since 856.4 mm was recorded on 113 rain days from January to October 2005.

Maximum temperature

Mean daily maximum temperatures were above average through the Perth Metropolitan area during October 2011, though sites close to the Perth hills were closer to average. Swanbourne registered a mean maximum temperature of 23.8 °C, 1.9 °C above average and the warmest October with respect to daytime temperatures in its 18 years of record.

The warmest day of the month across the Perth area was the 16th, when a strong high pressure in the Bight directed a dry and hot northeasterly airstream over western parts of WA. Daily maxima across Perth mainland sites ranged from the low to mid-30s, and were more than 10 °C warmer than normal for most sites. The 36.9 °C recorded at Gosnells City was the highest temperature of the month in the Perth region. The coldest day of the month across the Perth metropolitan area followed shortly after on the 18th, with daily maxima mostly in the 19 °C to 21 °C range on the coastal plain, whilst a maximum of 16.4 °C recorded at Bickley was the lowest daily maximum temperature of the month for the region.

Perth Metro's mean daily maximum temperature in October was 24.5 °C, which is the 3rd warmest October since records commenced in 1897, and follows on from last October's 24.6 °C, the 2nd warmest October on record. The warmest October on record at Perth Metro is 25.8 °C in 1969. Daily maxima in October 2011 ranged from a mild 19.8°C on the 18th, to a hot 36.3°C on the 16th.

Perth Metro's mean daily maximum temperature for the first 10 months of 2011 is 25.2°C, the warmest January to October period since records commenced in 1897. The previous record was 24.6°C in 1978, whilst the average for the same period is 23.9°C.

Minimum temperature

Mean minimum temperatures across Perth during October 2011 were very much above average, with several sites experiencing their warmest October nights on record. Rottnest Island recorded its warmest October in 35 years, since 1976, and 4th warmest October since records commenced in 1880.

Most nights were either mild or warm during the month, and the warmest night was the 16th, with daily minima in mid-to-high teens. Both Perth Metro and Swanbourne recorded a daily minimum temperature of 19.3 °C on the 16th, the highest overnight temperature of the month for the Perth area. The coldest night of the month was the 19th, with the daily minimum temperature of 4.9 °C at Pearce RAAF being the only temperature recorded below 5 °C for the month in the Perth metropolitan area.

Perth Metro's mean daily minimum temperature in October was 13.0 °C, which is the warmest October since records commenced at the Mt Lawley site in 1994. The average for October is 11.2°C. Daily minima ranged from a cool 7.2°C on the 14th to a warm 19.3°C on the 16th.

Wind and Sunshine

The greatest wind gust during the month in the Perth metropolitan area was 74 km/h recorded both Champion Lakes, on the 10th, and Perth Airport, on the 29th.

Perth recorded average daily sunshine of 8.6 hours in October 2011, 1 hours below the average of 9.6 hours per day, and the cloudiest October in Perth since 1993.

tails Extremes Records Summaries Important notes the top

Details Extremes Records Summaries Important notes the top

Details Extremes Records Summaries Important notes the top

Details Extremes Records Summaries Important notes the top

Details Extremes Records Summaries Important notes the top

Most values are the precipitation in the 24 hours to 9 am on the day indicated. Days marked with »» are part of a longer accumulation, which is marked like this on the final day. Values over 100 mm have been rounded to the nearest whole millimetre. Days marked with - have a rainfall report of zero; days left blank have no rainfall report (which often indicates no rain fell).
This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.

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